1. Field of the Invention
The invention relates to a light processing module for a projection display device, more particularly to a light processing module with a dust protection member for a projection display device.
2. Description of the Related Art
U.S. Pat. No. 5,327,270 discloses a polarizing beam splitter apparatus that includes a quarter wave plate arranged between a polarizing beam splitter and a light valve. The polarizing beam splitter transmits a first polarized component of an incident light along a first optical axis, and reflects a second polarized component of the incident light along a second optical axis. The quarter wave plate is arranged such that a fast or slow axis of the quarter wave plate is perpendicular to a plane containing both the first and second optical axes. In view of the arrangement of the quarter wave plate, increased brightness and improved contrast of a projected image can be achieved. However, since there is no dust protection mechanism employed in the apparatus, dirt can stick onto the light valve, which can result in an adverse affect on the quality of the projected image.
U.S. Pat. No. 6,530,665 discloses a dust protection member for supporting non-rotatably two polarizers on opposite sides of a liquid crystal panel such that dirt is unable to stick onto the liquid crystal panel, thereby preventing deterioration in optical characteristics of the liquid crystal panel.
The entire disclosures of U.S. Pat. Nos. 5,327,270 and 6,530,665 are hereby incorporated herein by reference.